The roof is the part of a building where failure becomes costly most quickly. Water ingress destroys insulation, the roof structure and, as a result, the rooms below. Roofers cover pitched roofs, replace individual tiles, install the roof underlay and insulation, and form the junctions to chimneys, dormers and roof windows. Re-roofing is also the most cost-effective opportunity to bring the insulation up to a modern standard.
A roofer covers roofs with clay or concrete tiles, slate or sheet metal, installs the roof underlay as a second water-shedding layer, adds the thermal insulation and forms the junctions to chimneys, dormers, roof windows and wall abutments. The work also includes repairs to individual areas, replacing broken tiles and regular inspections after storms or hail.
A few broken tiles are a repair job. But once the roof underlay has become brittle, signs of moisture are visible in the roof structure or the roof covering has reached the end of its life, repairs merely delay the inevitable. A tiled roof covering lasts around forty to sixty years, depending on the material. Anyone patching individual areas shortly before that point pays for the scaffolding twice.
For re-roofing with tiles, the rule-of-thumb figure is around CHF 150 to 250 per square metre of roof area; thermal insulation for the roof costs an additional roughly CHF 80 to 150 per square metre. These figures come from our guide to renovation costs. They exclude scaffolding, sheet metal work and repairs to the roof structure, which often only become apparent once the old covering has been removed.
As long as the roof is open, insulation costs little more than the materials and additional labour time. If it is retrofitted later, scaffolding and stripping the roof have to be paid for again. There are subsidy programmes from the Confederation and the cantons for energy-efficiency measures, but their conditions vary and applications usually have to be submitted before work starts. Clarify this before awarding the contract.
Ask for the roof area in square metres instead of a lump sum, and for separate itemisation of the roof covering, roof underlay, insulation, junctions and disposal of the old covering. Clarify who provides the scaffolding and who is responsible for repairs to the roof structure. An allowance for unforeseen issues in the roof structure should be included for every older building.
Roofers and sheet metal workers work on the roof, and on flat roof sections so do waterproofing specialists; carpenters are needed for the structure, and often photovoltaic installers as well. They all need the same scaffolding. Set the sequence before ordering the scaffolding, and record in writing who supplies the underlay membrane, counter-battens and metal flashings. This is exactly where the typical gaps between two quotations lie.